Silicone Fluid also known as polysiloxane, has a very stable silicon-oxygen bond, so it has good thermal stability and oxidation stability. At present, silicone oil used as lubricating oil mainly includes methyl silicone oil, methyl phenyl silicone oil and ethyl silicone oil. Methyl silicone oil is generally used as base oil for damping fluid and special lubricating grease; ethyl silicone oil is mainly used for precision instrument oil; methyl phenyl silicone oil is often used to make synthetic high temperature lubricating grease base oil because of its high temperature resistance, low pour point and good oxidation resistance;   
    The lubricating oil in the lubricating oil system is usually forced to circulate. It often enters some air in operation. When it stirs up, bubbles and bubbles will appear. The larger air bubbles can rise rapidly to the surface of the oil, and the smaller bubbles will rise slowly. No matter which form exists in the oil, it will bring adverse effects to the equipment, which may cause the oil pressure to go up and affect the oil circulation. Ring, destroy oil film, wear and tear, and at the same time, oil pressure is not stable, affect regulation. When the foam is spilt from the top of the tank and threaten the operation of the unit, the oil must have anti foam performance.

    In order to eliminate the foam produced by the working medium in the operation of the equipment system, after a long period of observation and research, a variety of defoaming methods have been found, such as physical defoaming, mechanical defoaming, chemical defoaming, etc. the chemical antifoaming method has the best effect and simple method, so it is widely used at home and abroad. In 1943, Shell Development Company and Gulf Research and Development Company found that liquid organic polysiloxane was a very effective antifoaming agent. At present, methyl silicone oil is still widely used as antifoaming agent for lubricating oil. Methyl silicone oil as an antifoaming agent is related to its following properties: surface tension is lower than lubricating oil, causing foaming agent to desorb, but its surface film strength is poor. (2) It has low solubility in lubricating oil, but it has a certain degree of lipophilicity. (3) Chemical property is not active and chemical reaction with lubricating oil is not easy. 4. Low dosage and good effect can effectively remove foam in lubricating oil even at high temperature. Methyl silicone oil has the advantages of low volatility, good viscosity-temperature, high flash point, low solidification point, good thermal stability and long service life. The commonly used viscosity of dimethyl silicone oil, which plays a defoaming role in lubricating oil, is 100-100 000 CS (25 C kinematic viscosity), and its usage is 5-50 mg/kg.

    Silicone oil is a liquid polysiloxane with excellent high and low temperature resistance, chemical stability, shear resistance, viscous-temperature properties and high compression rate. Vibration reduction products based on silicone oil are widely used in electronic and electrical equipment, high buildings, bridges and so on.

    The viscosity-temperature coefficient of silicone oil is lower than that of organic polymer with carbon chain structure, which is mainly due to the large bond angle and bond energy of silicone-oxygen-silicone bond in silicone oil molecular chain, the large degree of orientation freedom and good flexibility. Among all kinds of silicone oils, methyl silicone oil has the smallest temperature-viscous coefficient and the smallest temperature-dependent viscosity, so it is the most suitable base oil for damping fluid. With the increase of temperature, the viscosity of methyl silicone oil varies greatly at low temperature, but less at high temperature. Therefore, methyl silicone oil is a suitable damping material for use at higher temperatures. Silicone oil-based damping fluid has stable damping performance in a wide range of temperature and frequency. However, in order to further improve the damping performance of silicone oil, it is often necessary to add a certain amount of filler to increase the viscosity.

    In fact, because the molar mass of general methyl silicone oil has a certain distribution, it is multi-dispersive, which indicates that the distribution of the viscosity-temperature coefficient and the molar mass is also related. The required viscosity methyl silicone oil with lower viscosity-temperature coefficient can be prepared with different viscosity methyl silicone oil as the base oil of the damping fluid. The commonly used viscosity of dimethyl silicone oil as damping fluid (kinematic viscosity at 25 C) is 1000-10000cs.